Need help with this pleease help i dont know it

24-karat gold is considered to be pure gold. 18-karat gold is considered to be about 75% gold. what is 18-karat gold considered a mixture rather than a pure substance? a) it has a variable composition of other elements and minerals. b) its color is different than pure gold. c) the gold atoms are not arranged in a repeating pattern. d) it can be melted and transformed into a different substance.

Greg goes to a high school and observes the way students talk to each other. he makes notes on the words used, the atmosphere of the school and the way the students present themselves to each other. this is an example of a( research method.

Locate an article online from a news source that illustrates at least one determinant of supply. write a summary of the article, list the determinant(s) that were discussed in the article, and give a brief explaination of the effect of the determinant(s). you don't need to write the entire thing out, just find a source and tell me what i should include. i'm not the best at some parts of economics, and this is one of the parts i suck at.